1. Field of the Invention
The invention relates to a procedure for checking the operational capability of an electric circuit that has at least one sensor module comprising an integrated switching circuit and a diagnostic mechanism allocated thereto, wherein the sensor module has at least one output terminal connected to the diagnostic mechanism and power supply terminals to which an operating voltage is applied via cables.
2. Description of the Related Art
Such a procedure is disclosed in EP 0 962 748 B1. In this procedure, the sensor module is configured as a monolithic integrated circuit, which has a sensor for measuring a magnetic field and a measurement amplifier. The sensor is connected via the measurement amplifier to an output terminal of the sensor module for emitting an output signal. Furthermore, the sensor module has two power supply terminals to which an operating voltage is applied via cables.
In addition to the measurement signal, circuit measurements available within the sensor module are emitted via the existing outer terminals. The circuit measurements are thus superimposed as modulation signals on the supply current, the supply voltage, and/or the output measurement signal as diagnostic signals. Either the internal circuit measurements are emitted as an analog or digital modulation and the output signal as a digital value, or the internal circuit measurement values are emitted as a digital modulation and the output measurement signal as an analog value. Connected to the output terminal is a controller module, which checks the circuit measurements in order to generate a message regarding the capacity and the functional status of the module based on these measurements. The procedure has proven to have particularly useful practical applications, as with said procedure it is possible to detect wear of the mechanical components operating in conjunction with the sensor module at an early stage so that appropriate measures, such as replacement of the worn components, can be taken in time to avoid a failure. However, a disadvantage resides in the procedure in that in the event of a defect in the electric circuit, it is difficult to determine whether the sensor module or the cables are damaged.
The object is therefore to design a procedure of the abovementioned type that enables easy troubleshooting in the event of a defect in an electric circuit.